Fine carbon and method for producing the same

Abstract

A vapor grown fine carbon fiber including a hollow space along the fiber in its interior, and having a multi-layer structure, an outer diameter of 2 to 500 nm, and an aspect ratio of 10 to 15,000 is disclosed. The fiber has a center portion and a peripheral portion, and the center portion having a carbon structure different from that of the peripheral portion. A method for producing the fine carbon fiber, and a battery and gas occlusion material containing the fine carbon fiber are also disclosed.

What is claimed is:  
     
       1. A vapor grown fine carbon fiber comprising a hollow space along the fiber in its interior, and having a multi-layer structure, an outer diameter of 2 to 500 nm, and an aspect ratio of 10 to 15,000, wherein the fiber comprises a center portion and a peripheral portion, and wherein the center portion has a carbon structure comprised of carbon sheets aligned differently from carbon sheets that form the structure of the peripheral portion. 
     
     
       2. A vapor grown fine carbon fiber comprising a hollow space along the fiber in its interior, and having a multi-layer structure, an outer diameter of 2 to 500 nm, and an aspect ratio of 10 to 15,000, wherein the fiber comprises a center portion and a peripheral portion, and wherein the center portion has a carbon structure different from that of the peripheral portion, and wherein the hollow space of the fiber has a diameter (d0) and the fiber has an outer diameter (d) satisfying the following relation: 0.1d≦d0≦0.8d. 
     
     
       3. A vapor grown fine carbon fiber comprising a hollow space along the fiber in its interior, and having a multi-layer structure, an outer diameter of 2 to 500 nm, and an aspect ratio of 10 to 15,000, wherein the fiber comprises a center portion and a peripheral portion, and wherein the center portion has a carbon structure different from that of the peripheral portion and wherein the center portion of the fiber has a diameter (d1), the hollow space of the fiber has a diameter (d0) and the fiber has an outer diameter (d) satisfying the following relations: 1.1d0≦d1 and d1≦0.9d. 
     
     
       4. A vapor grown fine carbon fiber comprising a hollow space along the fiber in its interior, and having a multi-layer structure, an outer diameter of 2 to 500 nm, and an aspect ratio of 10 to 15,000, wherein the fiber comprises a center portion and a peripheral portion, and wherein the center portion has a carbon structure different from that of the peripheral portion and wherein the center portion of the fiber contains a herringbone-shaped carbon structure, and the peripheral portion of the fiber contains a concentric ring carbon structure. 
     
     
       5. The fine carbon fiber according to  claim 1 , wherein the hollow space is partially closed. 
     
     
       6. The fine carbon fiber obtained through heat treatment of a fine carbon fiber as recited in  claim 1  at about 2,000 to about 3,500 C. 
     
     
       7. The fine carbon fiber according to  claim 1 , further comprising boron or a boron compound. 
     
     
       8. The fine carbon fiber according to  claim 7 , wherein boron (B) is contained, in an amount of about 0.01 to about 5 mass %, in carbon crystals constituting the carbon fiber. 
     
     
       9. A fine carbon fiber mixture comprising a fine carbon fiber as recited in  claim 1  in an amount of about 5 to about 80 vol. % on the basis of the entire carbon fiber mixture. 
     
     
       10. A fine carbon fiber composition comprising a fine carbon fiber according to  claim 1 . 
     
     
       11. A gas occlusion material comprising a fine carbon fiber composition according to  claim 10 . 
     
     
       12. A secondary battery comprising an electrode material, wherein the electrode material is a fine carbon fiber composition according to  claim 10 . 
     
     
       13. The fine carbon fiber according to  claim 1 , wherein the center portion of the fiber contains a carbon structure in which carbon sheets are aligned substantially perpendicular to the axis of the fiber. 
     
     
       14. A vapor grown fine carbon fiber comprising a hollow space along the fiber in its interior, and having a multi-layer structure, an outer diameter of 2 to 500 nm, and an aspect ratio of 10 to 15,000, wherein the fiber comprises a center portion and a peripheral portion, wherein the center portion has a carbon structure different from that of the peripheral portion, and wherein the hollow space is partially closed at at least one point which is between the ends of the carbon fiber.